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Introduce sbreserve_locked(), which asserts the socket buffer lock on

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the socket buffer having its limits adjusted.  sbreserve() now acquires
the lock before calling sbreserve_locked().  In soreserve(), acquire
socket buffer locks across read-modify-writes of socket buffer fields,
and calls into sbreserve/sbrelease; make sure to acquire in keeping
with the socket buffer lock order.  In tcp_mss(), acquire the socket
buffer lock in the calling context so that we have atomic read-modify
-write on buffer sizes.
This commit is contained in:
Robert Watson 2004-06-24 01:37:04 +00:00
parent adb4cf0fbc
commit 3f11a2f374
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=131006
5 changed files with 68 additions and 20 deletions
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35
sys/kern/uipc_sockbuf.c
View File

@ -456,24 +456,26 @@ soreserve(so, sndcc, rcvcc)
{
struct thread *td = curthread;
if (sbreserve(&so->so_snd, sndcc, so, td) == 0)
goto bad;
if (sbreserve(&so->so_rcv, rcvcc, so, td) == 0)
goto bad2;
SOCKBUF_LOCK(&so->so_snd);
SOCKBUF_LOCK(&so->so_rcv);
if (sbreserve_locked(&so->so_snd, sndcc, so, td) == 0)
goto bad;
if (sbreserve_locked(&so->so_rcv, rcvcc, so, td) == 0)
goto bad2;
if (so->so_rcv.sb_lowat == 0)
so->so_rcv.sb_lowat = 1;
SOCKBUF_UNLOCK(&so->so_rcv);
SOCKBUF_LOCK(&so->so_snd);
if (so->so_snd.sb_lowat == 0)
so->so_snd.sb_lowat = MCLBYTES;
if (so->so_snd.sb_lowat > so->so_snd.sb_hiwat)
so->so_snd.sb_lowat = so->so_snd.sb_hiwat;
SOCKBUF_UNLOCK(&so->so_rcv);
SOCKBUF_UNLOCK(&so->so_snd);
return (0);
bad2:
sbrelease(&so->so_snd, so);
sbrelease_locked(&so->so_snd, so);
bad:
SOCKBUF_UNLOCK(&so->so_rcv);
SOCKBUF_UNLOCK(&so->so_snd);
return (ENOBUFS);
}
@ -503,7 +505,7 @@ sysctl_handle_sb_max(SYSCTL_HANDLER_ARGS)
* if buffering efficiency is near the normal case.
*/
int
sbreserve(sb, cc, so, td)
sbreserve_locked(sb, cc, so, td)
struct sockbuf *sb;
u_long cc;
struct socket *so;
@ -511,6 +513,8 @@ sbreserve(sb, cc, so, td)
{
rlim_t sbsize_limit;
SOCKBUF_LOCK_ASSERT(sb);
/*
* td will only be NULL when we're in an interrupt
* (e.g. in tcp_input())
@ -532,6 +536,21 @@ sbreserve(sb, cc, so, td)
return (1);
}
int
sbreserve(sb, cc, so, td)
struct sockbuf *sb;
u_long cc;
struct socket *so;
struct thread *td;
{
int error;
SOCKBUF_LOCK(sb);
error = sbreserve_locked(sb, cc, so, td);
SOCKBUF_UNLOCK(sb);
return (error);
}
/*
* Free mbufs held by a socket, and reserved mbuf space.
*/

35
sys/kern/uipc_socket2.c
View File

@ -456,24 +456,26 @@ soreserve(so, sndcc, rcvcc)
{
struct thread *td = curthread;
if (sbreserve(&so->so_snd, sndcc, so, td) == 0)
goto bad;
if (sbreserve(&so->so_rcv, rcvcc, so, td) == 0)
goto bad2;
SOCKBUF_LOCK(&so->so_snd);
SOCKBUF_LOCK(&so->so_rcv);
if (sbreserve_locked(&so->so_snd, sndcc, so, td) == 0)
goto bad;
if (sbreserve_locked(&so->so_rcv, rcvcc, so, td) == 0)
goto bad2;
if (so->so_rcv.sb_lowat == 0)
so->so_rcv.sb_lowat = 1;
SOCKBUF_UNLOCK(&so->so_rcv);
SOCKBUF_LOCK(&so->so_snd);
if (so->so_snd.sb_lowat == 0)
so->so_snd.sb_lowat = MCLBYTES;
if (so->so_snd.sb_lowat > so->so_snd.sb_hiwat)
so->so_snd.sb_lowat = so->so_snd.sb_hiwat;
SOCKBUF_UNLOCK(&so->so_rcv);
SOCKBUF_UNLOCK(&so->so_snd);
return (0);
bad2:
sbrelease(&so->so_snd, so);
sbrelease_locked(&so->so_snd, so);
bad:
SOCKBUF_UNLOCK(&so->so_rcv);
SOCKBUF_UNLOCK(&so->so_snd);
return (ENOBUFS);
}
@ -503,7 +505,7 @@ sysctl_handle_sb_max(SYSCTL_HANDLER_ARGS)
* if buffering efficiency is near the normal case.
*/
int
sbreserve(sb, cc, so, td)
sbreserve_locked(sb, cc, so, td)
struct sockbuf *sb;
u_long cc;
struct socket *so;
@ -511,6 +513,8 @@ sbreserve(sb, cc, so, td)
{
rlim_t sbsize_limit;
SOCKBUF_LOCK_ASSERT(sb);
/*
* td will only be NULL when we're in an interrupt
* (e.g. in tcp_input())
@ -532,6 +536,21 @@ sbreserve(sb, cc, so, td)
return (1);
}
int
sbreserve(sb, cc, so, td)
struct sockbuf *sb;
u_long cc;
struct socket *so;
struct thread *td;
{
int error;
SOCKBUF_LOCK(sb);
error = sbreserve_locked(sb, cc, so, td);
SOCKBUF_UNLOCK(sb);
return (error);
}
/*
* Free mbufs held by a socket, and reserved mbuf space.
*/

8
sys/netinet/tcp_input.c
View File

@ -2990,6 +2990,7 @@ tcp_mss(tp, offer)
* Make the socket buffers an integral number of mss units;
* if the mss is larger than the socket buffer, decrease the mss.
*/
SOCKBUF_LOCK(&so->so_snd);
if ((so->so_snd.sb_hiwat == tcp_sendspace) && metrics.rmx_sendpipe)
bufsize = metrics.rmx_sendpipe;
else
@ -3001,10 +3002,12 @@ tcp_mss(tp, offer)
if (bufsize > sb_max)
bufsize = sb_max;
if (bufsize > so->so_snd.sb_hiwat)
(void)sbreserve(&so->so_snd, bufsize, so, NULL);
(void)sbreserve_locked(&so->so_snd, bufsize, so, NULL);
}
SOCKBUF_UNLOCK(&so->so_snd);
tp->t_maxseg = mss;
SOCKBUF_LOCK(&so->so_rcv);
if ((so->so_rcv.sb_hiwat == tcp_recvspace) && metrics.rmx_recvpipe)
bufsize = metrics.rmx_recvpipe;
else
@ -3014,8 +3017,9 @@ tcp_mss(tp, offer)
if (bufsize > sb_max)
bufsize = sb_max;
if (bufsize > so->so_rcv.sb_hiwat)
(void)sbreserve(&so->so_rcv, bufsize, so, NULL);
(void)sbreserve_locked(&so->so_rcv, bufsize, so, NULL);
}
SOCKBUF_UNLOCK(&so->so_rcv);
/*
* While we're here, check the others too
*/

8
sys/netinet/tcp_reass.c
View File

@ -2990,6 +2990,7 @@ tcp_mss(tp, offer)
* Make the socket buffers an integral number of mss units;
* if the mss is larger than the socket buffer, decrease the mss.
*/
SOCKBUF_LOCK(&so->so_snd);
if ((so->so_snd.sb_hiwat == tcp_sendspace) && metrics.rmx_sendpipe)
bufsize = metrics.rmx_sendpipe;
else
@ -3001,10 +3002,12 @@ tcp_mss(tp, offer)
if (bufsize > sb_max)
bufsize = sb_max;
if (bufsize > so->so_snd.sb_hiwat)
(void)sbreserve(&so->so_snd, bufsize, so, NULL);
(void)sbreserve_locked(&so->so_snd, bufsize, so, NULL);
}
SOCKBUF_UNLOCK(&so->so_snd);
tp->t_maxseg = mss;
SOCKBUF_LOCK(&so->so_rcv);
if ((so->so_rcv.sb_hiwat == tcp_recvspace) && metrics.rmx_recvpipe)
bufsize = metrics.rmx_recvpipe;
else
@ -3014,8 +3017,9 @@ tcp_mss(tp, offer)
if (bufsize > sb_max)
bufsize = sb_max;
if (bufsize > so->so_rcv.sb_hiwat)
(void)sbreserve(&so->so_rcv, bufsize, so, NULL);
(void)sbreserve_locked(&so->so_rcv, bufsize, so, NULL);
}
SOCKBUF_UNLOCK(&so->so_rcv);
/*
* While we're here, check the others too
*/

2
sys/sys/socketvar.h
View File

@ -465,6 +465,8 @@ void sbrelease(struct sockbuf *sb, struct socket *so);
void sbrelease_locked(struct sockbuf *sb, struct socket *so);
int sbreserve(struct sockbuf *sb, u_long cc, struct socket *so,
struct thread *td);
int sbreserve_locked(struct sockbuf *sb, u_long cc, struct socket *so,
struct thread *td);
void sbtoxsockbuf(struct sockbuf *sb, struct xsockbuf *xsb);
int sbwait(struct sockbuf *sb);
int sb_lock(struct sockbuf *sb);